Savea's hat-trick against France made him the first player to score multiple hat-tricks at a single World Cup, having previously dotted down three times against Georgia. The treble in the French romp also took him to eight tries at the 2015 tournament, equalling the record for a single World Cup held by Bryan Habana (2007) and Lomu (1999).
Savea also surpassed Lomu in the all-time All Blacks try scoring ladder, with his 38 tries in 39 games looking impressive against Lomu's 37 tries in 63 contests.
Pietersen says he will have to be on top of his game to keep Savea under wraps.
"He is strong in contact, good under the high ball and he can also kick. So I will have to be at my absolute best to contain him," Pietersen said.
"But you live for challenges and on Saturday we'll both bring our best games and it should be a good battle - he will certainly bring the best out of me."
Savea has never scored against the Springboks - something Lomu also failed to do in his storied career.
It'll be Pietersen's quest to make sure that particular comparison continues after Sunday morning.